'Necessary' in the Bible

Therefore it is necessary that of the men who have accompanied us all the time that the Lord Jesus went in and out among us—

Paul and Barnabas spoke out boldly and said, “It was necessary that the word of God be spoken to you first; since you repudiate it and judge yourselves unworthy of eternal life, behold, we are turning to the Gentiles.

But some of the sect of the Pharisees who had believed stood up, saying, “It is necessary to circumcise them and to direct them to observe the Law of Moses.”